What inside popcorn makes it pop?
- "The heat"
- "The microwave"
- "Last time I ate popcorn not all of the seeds popped and my mom said I would brake my teeth if I tried to eat one [insert deep breath] but it didn't."
- "I like popcorn with butter."
- "I like popcorn with butter too!"
- ... so did the rest of the class but they obviously had to tell me one by one
I eventually managed to weave the conversation back to the topic of interest which was the origin of the pop. Well, drum roll please.
And the crowd stares in disbelief and confusion. Corn, originally from Mexico, has been cultivated world wide for thousands of years. Archaeologists have found corn kernels, corn pollen, and many other corn related things in the most unusual places. The oldest is 80 000 year old fossilized corn pollen found buried 61m (200ft) below Mexico City. [!] They've managed to pop 1000 year old popcorn grains found in a tomb on the east coast of Peru - the story does not state if they ate them or not.
Here's how it works. Within the hard yellow outer casing (pericarp), there is a pouch of soft starch that contains a small amount of water. At 450F or 232C water turns to vapour. As time goes by, the pressure caused by the expanding vapour increased to a point of rupture. This is when the outer casing exploded and the kernel is turned inside out and the popcorn goes everywhere if your not careful.
On that note, I'm off to make some popcorn.
Nasa.2004. What Makes Popcorn Pop?[on line] http://www.nasa.gov/audience/forkids/home/popcorn.html [accessed june 7th 2010]